Version 2.7 does not support iBooks/PowerBooks.
If you're still using an iBook/PowerBook, please download version 2.6.7 (which will also be updated in the future)
http://coconut-flavour.com/downloads/coconutBattery_2.6.7.zip

New in version 2.7:

[FEATURE] Added "current power usage" which will show you the current power usage of your MacBook or MacBook Pro in watt

[FEATURE] Added "Battery temperature" value which will show you the temperature inside your installed battery